13:13 GMT, April 20, 2009 Facing soaring costs and American opposition to the integration of Israeli systems into the F-35 Joint Strike Fighter, the Israel Air Force is showing some interest in Boeing's new F-15 Silent Eagle (F-15SE), The Jerusalem Post reported yesterday.

The F-15SE is a new configuration of the F-15 which has undergone improvements and modifications that could give the plane a stealth capability.

Improvements in stealth include coatings and treatments to the aircraft as well as a new design for the conformal fuel tanks that allows them to carry weapons rather than fuel.

Israel operates several squadrons of F-15s, including one of 25 F-15Is, the aircraft with the longest range in the IAF.The Silent Eagle will be capable of carrying internally air-to-air missiles, as well as air-to-ground weapons such as the Joint Direct Attack Munition (JDAM) and Small Diameter Bomb (SDB).

Defense Ministry Director-General Pinchas Buhris was scheduled to travel to the United States on Monday for talks at the Pentagon about the F-35.

Buhris will also seek to receive assurances from the new administration that the US will continue to fund the development of the Arrow 3 missile defense system.

Israel's interest in the new F-15SE stems from a number of considerations, but primarily from expected delays in the delivery of the JSF as well as the Pentagon's opposition to Israel's request to install Israeli-made systems in the aircraft, which is under development by Lockheed Martin.

While Israel decided last year to purchase the F-35, if political disagreements over the integration of systems continued, officials said it was possible interest in the newly-modified F-15SE would increase.

The Jerusalem Post first reported on the US opposition in February. In addition, the price of the F-35 is expected to pass the $100 million mark and would only arrive in Israel - if a deal is signed in the coming months - in 2014.

According to media reports, the new F-15SE will cost less and could arrive in Israel as early as 2011.

There is also an option to upgrade existing F-15s to the Silent Eagle model at a much lower cost. The US Air National Guard is also considering upgrading existing aircraft instead of purchasing new fifth-generation planes like the JSF and the F-22.

Boeing is studying the levels of radar cross-section (RCS) reduction possible with its F-15SE Silent Eagle in advance of licensing discussions with the U.S. government on possiblyexporting the stealthy fighter.

“It’s not how low can you go, it’s how low are you allowed to go, and the U.S. government controls that,” says Brad Jones, Boeing program manager for F-15 future fighters. “We can getto different levels depending on the country.”

Trade studies under way, including RCS chamber tests, will provide data for discussions with the government on what level of frontal-aspect stealth is releasable to each country interested in the F-15SE.

A major contributor to reducing RCS is the conformal weapons bays that replace the conformal fuel tanks now carried by F-15s. These allow a mix of air-to-air and air-to-ground weapons to be carried internally.

“We need to decide what to do in various areas across the aircraft to get to a specific level” of RCS, according to Jones. “There are many different techniques involved pending on the level of what we do and where we do it.”

Boeing is working to complete the RCS studies as soon as possible so it can start the licensingprocess, he says, adding that the first request for proposals from a potential customer is expected between mid-2010 and 2011 from South Korea.

The company is hoping the U.S. government will agree to release a frontal RCS level equivalent to that offered by the F-35 Joint Strike Fighter. “Internationally we are looking for a level playing field,” Jones says.

Meanwhile, trade studies are also under way for design of the F-15SE weapons bays, including whether electric, hydraulic or pneumatic power, or some combination, should be used toactuate the doors and deploy the weapons quickly.

These studies could involve potential international partners, and may take longer, Jones says. Some potential customers are interested in using the internal bays to house other payloads, including side-looking radar and broadband electronic-warfare jammers.

Since unveiling the F-15SE in March (Aerospace DAILY, March 18), based on customer interest, Boeing has done more work on a possible retrofit option, and the effect on the range of replacing the conformal fuel tanks.

A retrofitted F-15E, with the original straight tails, would lose 220-240 nautical-miles-radius of action depending on its mission. A new-build F-15SE would lose 180-200 miles because of thenew canted tails and digital fly-by-wire and electronic warfare (EW) systems.

“We take 1,500 [U.S.] gallons off the aircraft [by removing the conformal tanks], but the digital EW shrinks three systems into one so we can put fuel back in,” Jones says. “In theend we take 950 gallons off the aircraft.”

Digital fly-by-wire allows removal of the mechanical flight controls and saves weight and volume, while the canted tails generate lift at the back of the aircraft and allow 400-500 pounds of ballast to be removed from the nose.

With radar-cross-section (RCS) trials for Boeing’s Silent Eagle semi-stealthy F-15 prototype complete, company officials are now focusing on South Korea as a possible first customer.

The RCS testing took place during a two-week period last August and September, although Boeing has only just acknowledged it because of proprietary issues, says Mark Bass, vice president of F-15 programs.

The company is eyeing South Korea’s forthcoming F-X3 competition for 60 fighters as the first sales opportunity for the Silent Eagle. The South Korean parliament’s recent hesitancy about investing in all-stealth aircraft “validates our approach” with the aircraft, says Bass. The company is considering potential international co-development partners for a Silent Eagle conformal fuel tank, although no announcements have been made.

Boeing is developing the variant for international customers that already operate F-15s and are seeking additional aircraft. The system is a possible alternative for nations interested in the Lockheed Martin F-35 Joint Strike Fighter. The Silent Eagle is not as stealthy as the JSF, but it could provide flexibility for countries trying to stretch their defense dollars.

In the early days of an air campaign, the Silent Eagle can be outfitted with weapon bays suitable for carrying air-to-air and air-to-ground weapons that would be tucked inside conformal fuel tanks, thus reducing the aircraft’s front-quadrant RCS. The aircraft could then be reconfigured in hours to handle the F-15’s characteristic heavy load of weapons once early threats are removed and sustainment operations begin.

The RCS tests on F-15E1, an Air Force test asset leased to Boeing, took place at the company’s anechoic chamber in St. Louis. Various coatings were evaluated and a final candidate has been selected and applied to the appropriate portions of the airframe. Testing produced the desired results, he said. Bass declined to provide details on the coating or the precise RCS numbers.

The RCS testing took place with the standard vertical fins on the F-15, not the 15-deg. canted structures unveiled last year by Boeing (AW&ST Mar. 23, 2009, p. 29). Data needed about an optional canted tail can be gathered mathematically, Bass says.

The RCS testing is a step leading toward first flight, which is slated for late July. Boeing had planned first flight for the first quarter of 2010, but slipped the milestone to allow for the inclusion of suggestions from prospective customers regarding upfront design work.

Following first flight, the focus will shift to demonstrating the ability of the conformal tank to safely deploy an Advanced Medium-Range Air-to-Air Missile. The test is slated to be conducted at roughly 20,000 ft. at Mach 0.6, a benign scenario for the first shot. This demonstration will likely occur in July or early August, says Bass.

In the meantime, Boeing has applied for an export license and expects a ruling this spring.

Following the weapons demo, the team will turn its attention toward marketing and sales. Bass says the company has not tempered its hope of selling 190 Silent Eagles despite lackluster support from Israel, which is aggressively pursuing the F-35.

South Korea is expected to issue a request for proposals by early 2011 for new fighters. At a later date, Saudi Arabia may accept solicitations to replace up to 80 early model F-15s, says Bass. Singapore is also a possible customer.

Boeing has cited a rough cost for Silent Eagle of $100 million per aircraft, although that would depend on factors such as co-development plans that have not yet been established.

Boeing expects to receive an export license for its new F-15SE Silent Eagle within the month, a development that brings the company to openly pitch the jet to South Korea as a potential launch customer.

The Chicago-based defense giant has been in tentative talks with Seoul about the aircraft over the last year. However, it has not been able to openly market the semi-stealthy jet to international customers until it received clearance from the U.S. Government to sell low-observable technology abroad.

Boeing now expects to receive a government license to market the jet to foreign countries this month following a review of the jet's stealth technology by the U.S. Government, according to Brad Jones, Boeing's F-15SE program manager.

South Korea "has asked for information on Silent Eagle so now we've applied for the [license] and we hope to get that before the end of the month," said Jones, after a July company briefing with reporters in Arlington, VA. "As soon as the export license is provided, then I can provide [marketing] information to a country."

South Korea requested information on the jet in late 2009 and Boeing submitted its application to market the jet internationally in early 2010, according to company spokesman Damien Mills.

When the jet was unveiled in 2009, it was seen as a potential option to hedge against a possible fighter gap facing the U.S. Air National Guard, which may have to retire its oldest F-16s and F-15s before it is fully equipped with the F-35 Joint Strike Fighter.

However, in the year since, the Air Force has made it clear that it does not want to invest in any new fighter other than the F-35.

Boeing is pitching the Silent Eagle as a customizable fighter that can be outfitted with a host of upgrades, including active electronically scanned array radars, radar absorbent coatings, large digital cockpit displays, fly-by-wire software, canted tails and bolt-on internal weapons bays.

The price of each jet will depend on the equipment purchased by each government, according to Jones. While the radar, advanced avionics and even the weapon bays can be retrofitted to existing F-15s, the canted tails may have to be installed on new jets as they are built.

ST. LOUIS, July 9, 2010 -- The Boeing Company [NYSE: BA] Silent Eagle flight demonstrator aircraft F-15E1 completed a successful first flight on July 8 from Lambert St. Louis International Airport. During the 80-minute flight, F-15E1 opened and closed its left-side Conformal Weapons Bay, which contained an AIM-120 Instrumented Test Vehicle (ITV) missile. The ITV was not launched."The Silent Eagle demonstration flight validated our initial engineering design approach," said Boeing F-15 Development Programs Director Brad Jones. "Our intent was to verify all systems are operational in a flight environment. This flawless flight allows us to move into the next phase. In the next couple of weeks, we will ferry F-15E1 to the test range and launch an AIM-120.""Everything about the flight went according to plan," said Boeing F-15 Chief Test Pilot Dan Draeger. "We saw nothing unusual during the flight, and we cleared the desired flight envelope needed to fire the missile at the test range; that is pretty much unheard of on a first flight."The Silent Eagle is an innovative design solution developed in response to international customer requirements for a cost-effective, high-performance fighter aircraft to defend against future threats. The F-15SE offers unique aerodynamic, avionic and Radar Cross Section reduction features that provide the user with maximum flexibility to dominate the ever-changing advanced threat environment. The aircraft's Conformal Weapons Bays can carry a variety of air-to-air missiles and air-to-ground weapons.